US2551573A - Pyrolysis of chloro-fluoro alkanes - Google Patents

Description

Patented May 8, 1951 'UNlTED SES PYROLYSIS OF CHLORO-FLUORO ALKANES N Drawing. Application November 30, 1945,

Serial No. 632,116

13 Claims.

This is a continuation-in-part of our earlier filed applications Serial No. 435,064, now Patent No. 2,387,247, and Serial No. 475,526, filed February 11, 1943.

This invention relates to the preparation of organic fluorine compounds by pyrolysis. By pyrolysis, we mean the transformation of a compound into another substance or other substances through the agency of heat alone. (Hurd, The Pyrolysis of Carbon Compounds, p. 9) The term pyrolysis used in this specification therefore will include not only the decomposition of compounds but also the making of more complex compounds. In the applications identified as Benning et al., Serial No. 344,666, filed July 10, 1940, now Patent No. 2,365,516, and Benning Serial No. 379,473, filed February 18, 1941, now Patent No. 2,343,252, are disclosed two processes involving a reaction between a fluoro-hydrocarbon and HCl in the presence of a catalyst. Those reactions may be described as additive, since their apparent course is the addition of HCl to the olefine in the place of double bonds. These reactions were carried out at comparatively low temperatures, in most cases below 350 0., because those temperatures were satisfactory and because observations of a limited number of experiments at higher temperatures showed the existence of what were thought to be undesirable side reactions. We have now discovered that the side reactions are pyrolytic and of a fundamentally difierent nature than HCl addition, and that they and other reactions that occur at elevated temperatures can be put to valuable use.

It is an object of this invention to produce organic compounds by pyrolysis. Another object of the invention is to produce compounds which are useful, by methods which are economically and technically satisfactory. Another object of the invention is to produce new fluoro hydrocarbons. A particular object of the invention is to synthesize organic compounds having fiuoroalkyl chains by the pyrolysis of fluorohalogeno carbon compounds. Another object of the invention is to produce the compound CF2=CF2 by methods which are technically and economically satisfactory.

According to our invention iluoro-chloro alkanes, which may otherwise be called fluorochloro saturated aliphatic compounds, are made into other compounds by pyrolysis. This reaction may be carried out in isolation, or in the presence of a catalyst, by which we mean a substance that aifects the result without combining withthe reactants. Inert gases such as dehydrochlorination predominates.

hydrogen, or chlorine, substituents. Fluorochloro-alkanes, containing at least one displaceable hydrogen, are preferred as starting materials. Among the particular materials that have been pyrolyzed by the process of this invention are those recited in the examples given hereinafter in extenso, and CHzClF, CH3CC12F, CHzClCClFz, C2HC12F3 and CClzFCClFz. Differences have been observed in the efiect of pyrolysis on saturated and unsaturated compounds.

When fluoro-chloro-alkanes, containing one or more displaceable hydrogen atoms, are pyrolyzed,

Such dehydrochlorination may be intermolecular or intramolecular, depending upon the relative positions of the hydrogen and chlorine atoms in the molecule. Where the hydrogen and chlorine atoms are on a single carbon, the reaction appears to involve primarily an intermolecular dehydrochlorination, wherein the elements of the hydrogen chloride are obtained from difierent molecules, to produce free radicals which condense to form compounds of higher molecular weights. For example, when Cl-IClFz is pyrolyzed, one molecule may lose a hydrogen and another may lose a chlorine to form the free radicals CC1F2 and CI-IF2, which radicals may further pyrolyze to the free radical =CF2. Such free radicals condense to form compounds of higher molecular weight, represented by CF2=CF2, CClFzC'HFz, C4Fs and the compounds of the series H(CF2)nCl in which n is at least 3 with the compounds of increasing molecular weight being produced in diminishing propor-' tions. The compounds of the formula H(CF'2)1LC1 are open chain compounds with the H and C1 atoms on opposite terminal carbon atoms and they may be represented more accurately by the formula HCF2(CF2) nCFZC]. where n represents at least one.

Where the hydrogen and chlorine atoms are on adjacent carbon atoms, the reaction appears to involve primarily an intramolecular dehydrochlorination, wherein both elements of the hydrogen chloride are obtained from the same molecule, to produce fluoro-olefines which have a tendency to polymerize. For example, the pyrolysis of CClFzCHFz produces primarily C2F4 and C4F8, octafluorocyclobutane.

Where the hydrogen and chlorine atoms are on different non-adjacent carbon atoms, the reaction appears to involve both an intermolecular dehydrochlorination and a splitting of the molecule to produce compounds of lower molecular weight. For example, the pyrolysis of compounds of the formula H(CF2)11.C1 produces C2F4 and the other lower members of the series mormcl. Where the fiuoro-chloro-alkane contains no hydrogen, the pyrolysis may result in a disproportionation, as for example in the pyrolysis of CClzFz which produces CFi and CFsCl along with other products. In the case of compounds hav-' ing more than one carbonatom, cleavagemay result, followed by reproportionation of the halogen among the fragments e. g. CF2C1CF2'C1 yields CF2C12 and CF3C1 among other products.

The preferred starting materials of our inven-'- tion are the hydrogen-containing fluoro-chloro alkanes in which the H and Cl atoms are on a single carbon, and particularly 'CHClFz. The next most preferred starting materials are the hydrogen-containing fiuoro-chloro-alkanes having H and Cl atoms on adjacent carbons. vAlthough for the production of particular compounds the reaction will be carried out under well-controlled conditions of time, temperature and pressure, complex mixtures of compounds of various molecular weights can be produced by subjecting the compounds to pyrolytic conditions for extended periods of time. Pressures may also be used to vary the results, although for the purposes of economy and safety each particular reaction should be carried out with the lowest pressure consistent with optimum results. For example, pressures of four atmospheres absolute have been found satisfactory in many cases. In general, operations may be carried out at pressures between 0.1 and atmospheres absolute, but other pressures are useful and may be employed when an increase in efficiency will result.

This is a pyrolytic process. The disintegration and integration are produced essentially by heat. It is, therefore, important to select a temperature which will efliciently produce the reaction. The temperature should be selected to give optimum production of the desired product. We have found that excellent pyrolytic results have been produced at temperatures between 600 and 1000 C., but that particular substances have been pyrolyzed at temperatures as low as 400 C. and above 1000 C. under appropriate conditions of time and pressure. Electrical heating is efficient, but any method of heating may be applied. The temperatures which are used must also be chosen in view of the materials that compose the re- .action apparatus.

The time of exposure of the reactants to the pyrolytic conditions is a matter of considerable importance where a particular product is desired. Extending the period of exposure frequently produces compounds of increased molecular weight.

In general, the pyrolysis proceeds to the integration of new fluoro hydrocarbons efiiciently in the absence of catalysts. Catalysts are generally useful in altering the course of the pyrolysis by splitting off more fluorine, rather than in improving its efiiciency. Heavy metal halides and halides of the alkaline earth metals, such as BaClz and CaClz have been used.

The process is preferably carried out continuously by passing the convertible material through a tube heated to a pyrolytically effective temperature. The tube should be composed of a material which is inert to the reaction and the reaction products. Carbon and the noble metals are sufliciently inert and have proved to be satisfactory materials for the construction of reaction chambers. The chamber need not be wholly composed of the inert material, but may be lined with it. Reaction chambers containing a platinum lining are particularly satisfactory. The process may be carried out in batches rather than continuously, but continuity is preferred.

The following examples have been carried out and have been selected for inclusion in this specification because they show a number of the compounds which have been successfully pyrolyzed, and a number of classes thereof, and a variety of reaction conditions. The applicants present these examples, not as constituting any limitation of the work which has actually been done, but as sufficiently representative to enable persons skilled in the art to practice the invention. In these examples the terms conversion and amount converted include the assumption that the disappearance of one mol of the primary organic material resulted in the liberation of one mol of halogen acid. This assumption is warranted by the close agreement between the figures for conversion obtained by acid analysis and the actual primary material which disappeared. Unless otherwise noted, the examples were carried out at a pressure of about one at-' mosphe're. The temperatures of the pyrolyses were measured with a thermocouple which was placed in contact with the outer surface of the reaction tube near the center of the heated zone, so that the true average temperature of the gases in the tube may have been somewhat lower than the values given.

Example I One hundred eighty grams of CHClF'z were passed through a silver tube 8.0 mm. I. D. x 700 mm. long at a rate of about g./hr. while the pressure in the tube was kept at approximately one atmosphere abs. The tube temperature was maintained at about 700 C. over an estimated length of 200 mm. by electrical heating. The reaction products were washed with water, dried and condensed in receivers cooled to about 70" C. The crude organic products (156 g.) were This was equivalent to a disappearance of 28% of the CHClFa fed and a yield of C2F4 therefrom of 83%.- Analysis of the washwater for acid indicated that a conversion of 27% had taken place.-

Eaidmple II CHClFz was thermally decomposed in an ap paratus similar to that described in nxampie I while being maintained at a ressure or 4 atrii. absolute. The organic flow rate was about 387 g./hr and the operating temperature about 700 C. A conversion of 23% was obtained under these conditions. The acid free organic products Example III CHClFz containing 2.7 wt. per cent CHChF was passed through a tube which was made of base metal resistant to oxidation at high temperatures and lined with a thin layer of platinum. The flow rate was such that a conversion of about 24% was obtained, while the tube temperature was maintained at about 700 C. The reaction products were analyzed, after removal of acid constituents, and found to contain almost nothing else but 02F; and the starting components.

Example IV CHCIF2 was passed over a catalyst of activated carbon contained in a nickel jacketed carbon tube, 18.8 mm. I. D. x 600 mm. long. The tube was heated to about 300 C. and the-flow of CHClFz maintained at about 55 g./hr. Under these conditions a 3.5% conversion to other products was obtained as determined by acid analysis. This compares with a conversion of about 1% which was obtained at 525 C. in the absence of any catalyst.

Example V CI-IClFz was passed over a catalyst consisting of iron and iron halides formed during pyrolysis contained in a nickel jacketed graphite tube which was heated to about 675 C. The CI-IClFz flow rate was such that a conversion of 24% was obtained. Under these conditions, 13 mole per cent of the acid formed was HF. The thermal decomposition of CHClFz under similar conditions in the absence of a catalyst resulted in the formation of less than 5 mole per cent H35 in the acid evolved.

Example VI The thermal decomposition of CHClFz in the presence of a catalyst consisting of deoxidized copper and copper halides formed during pyrolysis was carried out in a manner similar to that described in Example V. The results obtained were also similar, the HF content of the acid being raised from less than 5 mole per cent to about 13 mole per cent upon introduction of the catalyst into the graphite tube.

7 Example VII 'CI-IClFz was passed over a catalyst contained in a nickel jacketed graphite tube heated to about 620 C. The catalyst consisted of an alloy made up of 58% Ni, 20% Fe, 20% Mo and 2% Mn and any of the corresponding metal halides 6 formed during the pyrolysis. The CHCIFZ flow rate was such that a conversion of 25% was obtained. Under these conditions 7.5 mole per cent of the acid evolved as HF. Analysis of the reaction products after removal of the catalyst showed a conversion of 26%.

Example VIII CHClFz (B. P. 40.8 C.) was treated in a manner similar to that described in Example I, the flow rate being maintained at about 57 g./hr. and the temperature at about 700 C. A conversion of 49% was obtained as compared with a conversion of 27% at the higher flow rate used in Example I.

Example IX Provision was made to operate the apparatus described in Example I at an absolute pressure of 0.5 atm. CHClFz (B. P. 40.8 C.) was passed through the tube at a rate of about 35 g./hr. and a temperature of about 700 C. The reaction products were washed with water, dried and condensed in receivers cooled to about and C., respectively. Acid analysis showed a conversion of 50%. The composition of the crude was as follows:

Amount Present, Volume Per Cent Component CzFi CHCIF: Material boiling above 40 C A 02F; yield of 89% was obtained.

Example X CHC1F2 recovered from a previous pyrolysis was treated in a manner similar to that described in Example I. The temperature was maintained at about 700 C. and the conversion at about 26%. The isolated yield of C2F4 from the pyrolysis products was found to be 89% of theory. The converted material was found to contain 96 volume per cent of C2F4.

Example XI In a large scale pyrolysis of CHClFz under conditions similar to that used in Example I, a large amount of material boiling above -40 C. was obtained. The following are among the compounds which were isolated and identified. Some of their physical constants are given.

. Compound M01. Wt.

B. Pt. Density nD Cale. Found HCsFwCI- HCqFnCL HC F CL dfi=L 661 ai=1.7as

d=1. 77s d=1.s1 solid at room temperature. M. Pt. 52 0 lilss umes PV= RT which for compounds of this type gives a M. W. from 2 to 4% g 1 Calculated. v

' 'The material, boiling over -40 C., also con tained higher boiling members of the series H(CF2) 11.01, probably including those wherein n is 15 to 20, but the amounts obtained were insuffici'ent to permit accurate identification. Several constant boiling mixtures were also found in the pyrolysis material; one of them boiled at about 12 C. and contained about 80 vol. per cent of C2HC1F4; together with a component which boiled at '4 C. and had a molecular weight of about 202. Another azeotrope boiled at about 8 to 9 C. and contained about 90 vol. per cent of CHClzF. A third constant boiling mixture had a boiling point of 4 Example XII The pyrolysis of CHClFz was carried out in a platinum-lined Inconel-jacketed nickel tube, 13.7 mm. ID. X 108 cm. The reaction products were washed with water, dried and condensed in two receivers. ne pyrolysis was carried out at 30%, 77% and 100% conversions and the proportion of the various fractions in the high boilers determined by distillation. These results are summarized as follows:

various conditions of temperature, pressure and conversion are given in the table:

Pyrolysis of CHCIF: Under Pressure N i s. m.

Abs. Pyr oysis, ggggg l gp r e egl i t I Sioll Boilers" 1 1 The percent fhigh boilers is based on the amount of CHClF which d sappeared in the reaction by pyrolysis.

The above table shows'that an increase in pressure generally results in the increase of the percentage of high boilers obtained in the pyrolysis. Although the composition of these products varied in each run, over a boiling range of 12 to over 190 C., over 65% of the high boilers were H(CF2)3C1 and H(CF2)4Cl.

1 This value is the ratio of amount of H. B. obtained to the total CHClFz passed through the pyrolysis tube.

Erample XIII CHClF2 was passed through a nickel-jacketed carbon tube, 18.8 mm. ID. x 600 mm. long at a rate of 82 g. per hour. The temperature was maintained at about 700 C. and the conversion at about 24%. A coil of gold wire was then placed in the center of the heated zone and the pyrolysis continued for five hours in the presence of the test piece. The conversion and the HF splitoff remained the same and no change was noticed in the composition of pyrolysis products. The corrosion rate on this test piece was found to be less than 0.1 X 10 inches per month penetration. This rate is of the same order of magnitude as that for platinum used under similar conditions for the pyrolysis of CHClFz.

Example XIV A platinum-lined, Inconel-jacketed nickel tube, 42" x 0.5" ID. was used in the pressure pyrolysis of CHClFz. The pyrolysis temperature was maintained over an estimated length of 20 cm. by electrical heating. The desired pressure and conversion were maintained by control of the temperature and flow of the organic material. The reaction products were then washed, dried and condensed in receivers cooled in carbonice-acetone baths. No attempts were made to collect any of the gases passing through the carboniceacetone traps. The liquid condensates were then Example XV Example XVI CF3CH2C1 was passed through a platinum-lined Inconel-jacketed nickel tube, 13.7 mm. I. D. x 108 cm., at a rate of about 110 g. per hour while the temperature in the tube was kept at about 615 C.

distilled in a laboratory helices-packed column I and the amount of CI-IClFz destroyed by the process thus determined. 7

The results of the pyrolysis of CHC1F2 under over an estimated length of 200 mm. by electrical heating. The reaction products were .washed with water, dried and condensed. Acid analysis showed a conversion of about 52%. The following compounds were isolated and identified in the product:

CI-IF's (B. P. 8l C.) with a vapor density of 2.217 g. per liter at 22 C. and 59 0 mm.

C3H3F5 (B. P. 19.6) with a vapor density of 5.06 g. per liter at 27 C. and 760 mm.

C LHBClFG (B. P. 35-36") with a vapor density of 5.272 g. per liter at 24 C. and 480 mm.

Example XVII CHClzF was passed through a platinum-lined tube similar to that described in Example I at a.

rate of 121 g. per hour and with a tube temperature of about 675 C.

Dichlorodifiuoroethylene (C2C12F2), B. P. 21- 22 C., C2CI4F2, B. P. 92-93 C., and C3H2C13F3, B. P. 108 C., were isolated and identified in the product.

Example XVIII CHsCClFz was passed through a platinumlined Inconel-jacketed nickel tube, 13.7 mm. I. D. x 108 cm. long, at a rate of about 120 g. per hour. The tube temperature was maintained at 715 C. over an estimated length of 200 mm. by electrical heating. The reaction products were washed with water, dried and condensed in two receivers. The first receiver was cooled to about 70 C. while the second receiver was cooled in a bath of liquid nitrogen. Acid analysis of the wash water showed a conversion of about 50%. The pyrolysis of this hydrocarbon proceeded smoothly to the formation of substantially pure CH2CF2. The boiling point of this material is 82 C., and its vapor density at 28 C. and 756 mm. was 2.58 g. per liter.

Example XIX CHF2CC1F2 Example XX About 5 g. per hour of CH2=CC1F (B. P. -27) was passed through a platinum-lined Inconeljacketed nickel tube, 13.7 mm. I. D. x 108 cm. The temperature range covered was from 780 to 930 C. The reaction products were washed with water, dried and condensed in two receivers. This crude reaction product had a boiling range of 30 to +20 C. with definite fractions boiling at about C. and 20 C.

Example XXI H(CF2)3C1 (B. P. 21 C.) was passed through a platinum-lined Inconel-jacketed nickel tube, 13.7 mm. I. D. x 108 cm., the flow rate being maintained at about 118 g. per hour and the temperature at about 780 C. Acid analysis showeda conversion of about 46%. A total of about 189 g. of crude organic products were collected. The following compounds were isolated and identified in the pyrolysis products: C2F4 and CClzFz which have boiling points of -76 C. and 30 C., re-

spectively. Another fraction boiling at 12 C.

with an M. W. of 164 was obtained which was an azeotropic mixture of C4Fa (octafluorocyclobutane) and CHF2CC1F2.

Example XXII In the pyrolysis of CHClF'z to C2F4 there was obtained some reaction products Whose boiling range was from 12 C. to about 250 C. This fraction, designated the high boilers and which was a mixture of the compounds having the formula -H(CF2)1LC1 was subjected to pyrolysis at 740 C. in a platinum-lined Inconel-jacketed nickel tube, 13.7 mm. I. D. x 108 cm. with the conversion at about 40%. The recovered material was washed, dried and fractionated; The fraction boiling above 12 C. was then subjected to a second pyrolytic treatment under similar conditions as in the first. Although the temperature of the tube was, raised to 840 C. the conversion remained fairly constant at 20%. After Washing and drying, the pyrolysis material was again fractionated. The successive pyrolyses of the high boilers did not result in the intended building up of carbon chains. Instead there was a definite breakdown in the molecule to produce a mixture, containing the same compounds as the starting mixture but with an increase in the proportion of the lower boiling members. The composition of the original high boilers and those of the pyrolyzed materials was as follows:

Percentage composition based on total high boilers.

Example XXIII CC12F2 was passed through a platinum-lined Inconel-jacketed nickel tube, 19 mm. I. D. x 60'-' long at a rate of about 23 g. per hour. The sur;- face temperature was maintained at about 950 970 C. over an estimated length of 200 mm. by electrical heating. The reaction products were washed with sodium sulfite solution, dried and condensed in receivers cooled to 76 C. followed by a tailing receiver cooled in liquid nitrogen. About 3 g. of CE; was foundin the liquid nitrogen trap. This material had a boiling point of 129 C. and a molecular weight (vapor density method) of 90. (Calculated for CF 1, 88.) The 76 condensate, totalling about 66 g., was distilled and the following compounds isolated: about 7 g. of CF3C1, boiling point 81, also about 1.5 g. of fraction boiling above 40 C. which was not identified. The rest of the condensate was the original starting material, CC12F2 boiling at -29 to -30 C. Analysis of the Wash water showed the presence of HF, I-ICl and free chlorine;

Example XXIV CClF'zCClFz was pyrolyzed in a platinum-lined tube similar to that described in Example XXIII at a tube temperature of about 880 C. About 170 g. of material was passed through in 1.25 hours at a contact time approximating 2-3 seconds. Extensive decomposition was evident and free chlorine was detected. The reaction products were washed free of acid constituents, dried and fractionated. About g. of CF3C1 and about 12 g. of CF2C12 were isolated and identified. High boiling constituents (boiling above 4 C.) were obtainedbut were not identified.

The reaction products may be washed with water or alkaline solution to remove acid constituents before condensation and analysis, although this is not necessary. In some cases, it is advantageous to separate certain desired components before acid removal. 1

The process produces both saturated and unsaturated products. A very important olefine which is efiiciently produced by the process is .CFz cFc, which is a valuable intermediate for refrigerants and plastics. Among'the saturated compounds which are produced are mono carbon fluorides, such as CCIF3, and fluorides having a served that the products tend to increase .in stability as they approachsaturation by fluorine; for example, the compound =CI-IF3 is very stable; in several cases the substitution of fluorine for chlorine has produced a decrease in the reactivity of the compound. Because of this, the process is a particularly satisfactory method of producing reactions of the type described among fluoro compounds containing chlorine.

The compounds of the series H(CF2)12C1 where .in n is at least 3 are new and valuable compounds. They are very much more stable to heat and chemical reagents than the next lower homologue whereby they may be employed under conditions, "such as reaction media, heat transfer media and the like, where the next lower homologue would not be practical. For example, when TH CCFzJ 2C1 is heated to 150 C. under pressure with 1.5 moles of alcoholic potassium hydroxide for hours, part of the material was dehydrochlorina'ted to CF2=CF2 and other products. When each of H'(CF2) 4C1, H(CF2 5C]. and HKCFzlsCl were treated in the same "manner at temperatures as high as 175C, no dehydrochlorina'tion took place. Also, when H(CF2) 201 was heated with1l2 moles of zinc dust in an excess of absolute methyl alcohol "for 5 hours at 150 C. under pressure, chlorine and fluorine were split out to produce 'CHFzCFz. When each of Hi-CFzMCl, I-I(-CF2-) 4C1, H'(CF2-) 5C1 and II(CF2) 601 were treated in the same manner at temperatures up'to 170 'C., no detectable amounts of the corresponding'olefine were obtained.

The particular advantage of the invention is that a 'pyrolytic process has been discover'ed'for the production of new compounds and for :the more efii'cien't production of old compounds, which is characterized by its simplicity and the ease with which it ma be operated. The invention provides an efficient method of producing organic com-pounds containing fluorine, particu- :larly fiuorinate-d olefines. These-compounds have uses in themselves, such as for refrigerants, anaesthetics, and solvents and are useful as intermediates for the production of alcohols, esters, halides, and .alkyl derivatives. A particular advantage of the invention is that the process is most efficient for the production of the valuable compound CFz=CFz, which is an intermediate of wide utility. The invention is 'also useful for the synthesis of compounds having more carbon atoms than the'compound pyrol-yzed, and for the extension .of carbon chains. The process in volves the pyrolysis of compounds of both light and heavy .molecular weight. The pyrolysis has been carried out in both .acontinuous and a stepwise .manner, and a large variety of conditions has been employed, so that it :is beyond'question that the process is of generalapplication.

.As :many apparently widely different embodiments of this invention may be .made without 12 departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments thereof except as defined in the appended claims.

We claim:

1. The process of converting fluoro-chloroalkanes to different fluorine containing organic compounds which comprises pyrolyzing a fluoroc'hloro-alkane of from 1 to 3 carbon atoms containing at least one hydrogen atom and in which each carbon carrying a flourine atom also carries at least one additional halogen atom of the group consisting of chlorine and fluorine, at a temperature between 600 C. and 1000 C.

2. The process of converting fluoro-chloroalkanes to different fluorine containing organic compounds which comprises pyrolyzing a fluorochloro-alkane of from 1 to 3 carbon atoms containing both a hydrogen atom and .a chlorine atom on a single carbon atom and in which each carbon carrying a fluorine atom also carries at least one additional halogen atom of the group consisting of chlorine and fluorine, at a temperature between 600 C. and 1000 C.

3. The process of converting fluoro-chloroalkanes to different fluorine containing organic compounds which comprises pyrolyzing a fluoroch'loro-alkane of from '1 to 3 carbon atoms containing a hydrogen atom and a chlorine atom on adjacent carbon atoms and in which each carbon carrying a fluorine atom also carries at least one additional halogen atom of the group consisting of chlorine and fluorine, .at .a temperature between 600 C. and 1000 C.

4. The process of producing the compound represented vby the formula CF2=CF2 which comprises pyrolyzing the compound represented by the formula CHClFz.

5. The process of producing the compound represented by the formula CF2=CF2 which comprises pyrolyzing the compound represented by the formula CHClFz under pressures between 0.1 and 10 atmosphere absolute.

6. The process of producing the compound represented by the .formula CE2=CF2 which comprises pyrolyzing the compound represented by the formula CHClFz at a temperature between 600 C. and 1000 F. at atmospheric pressure.

'7. The process of producing .the compound represented by the formula CF2=CF2 which comprises heating the compound represented by the formula CHClFz at a temperature of about 700 C. in a platinum reaction vessel, condensing the product, and separating its constituents.

8. The process which comprises pyrolyzing CHClFz by passing it through anoble metal tube heated to a temperature of about 700 0., washing the reaction products with water, drying the reaction products, condensing them, and subjecting them to fractional distillation.

9. The process which comprises pyrolyzing CHClFz by passing it through a noble metal tube at a temperature of about 700 C. ata pressure of about four atms. absolute, washing the product with water, drying it, condensing it, and isolating its constituents by fractional distillation.

10. The process of producing the compound represented by the formula CH2=CF2 which comprises heating CH3CC1F2 .at temperature of from about 600 .C. to about 1000 C. for suficient time .to convert a substantial portion of the CH3CC1F2 t0 CH2=CF2.

11. The process of producing the compound represented by the formula C2F4 which comprises heating CC1F2CI-IF2 at temperature of from about 600 C. to about 1000 C. for sufiicient time to convert a substantial portion of the CC1F2CI-IF2 to 02R; and other products.

12. A compound represented by the formula:

mcFmci in which n is an integer of from 3 to 14.

13. The compound represented by the formula:

FREDERICK B. DOWNING. ANTHONY F. BENNING. ROBERT C. MOHARNESS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Swaney et a1. May 15, 1945 Henne et a1: J. A. C. 8., vol. 58, pages 402-3 Senderens: Bull. Soc. Chem. de France, 4th Series, v01. 3,- pages 823-829 (1908).

Fieser and Fieser: Organic Chemistry (1944) page 32.

Gilman: Organic Chemistry (2nd ed. 1943), vol. I, pages 956; 959 to 961.

Henne etaL: J. Am. Chem. Soc., vol. 58, pages 882-884 (1936).

Ruff et a1.:'-Zeit. fiir anorg. und allgemeine Chemie, vol. 201, 256-7 (1931).

Nuckols et a1.: Chem. Abs., vol. 28, 2079 (1934)

Claims (1)

1. THE PROCESS OF CONVERTING FLUORO-CHLOROALKANES TO DIFFERENT FLUORINE CONTAINING ORGANIC COMPOUNDS WHICH COMPRISES PYROLYZING A FLUOROCHLORO-ALKANE OF FROM 1 TO 3 CARBON ATOMS CONTAINING AT LEAST ONE HYDROGEN ATOM AND IN WHICH EACH CARBON CARRYING A FLOURINE ATOM ALSO CARRIES AT LEAST ONE ADDITIONAL HALOGEN ATOM OF THE GROUP CONSISTING OF CHLORINE AND FLUORINE, AT A TEMPERATURE BETWEEN 600* C. AND 1000* C.